The present invention relates to delivery of therapeutic agents. More particularly, the present invention provides apparatus and methods for minimally invasive, localized delivery of sclerotherapeutic agents within a body lumen.
Varicose veins are bulged sections of blue, twisted veins, normally found on a person""s calf or thigh. In the United States alone, approximately 25 million people suffer from varicose veins. The condition is often hereditary and is most common in women. Onset may first occur during pregnancy, due to hormonal changes and increased pressure in the veins during uterus expansion. Obesity, menopause, aging, and repeated abdominal strain may also be contributing factors.
Veins carry oxygen-depleted blood back toward a person""s heart. In a healthy persons one-way valves within the veins prevent backward flow of the blood away from the heart. In people with varicose veins, the valves may leak or may be absent, causing blood to accumulate and stretch the veins. Alternatively, weakness in the vein walls may cause pooling of the blood. Less commonly, congenital abnormalities or vascular diseases, such as phlebitis, may lead to accumulation. Regardless of the cause, the accumulated blood creates-unsightly lumps and kinks just under the skin.
In addition to cosmetic concerns, varicose veins may ache or itch, and may cause swelling and pain in the feet and ankles. Varicose veins tend to be progressive. Some affected people, especially those with more moderate symptoms, are able to reduce and/or control the condition through exercise, weight control, wearing of compression stockings, leg elevation, and/or avoidance of long periods of standing or sitting.
For more advanced cases, a variety of treatment options exist. The two most common are xe2x80x9csclerotherapyxe2x80x9d and vein xe2x80x9cstrippingxe2x80x9d. Sclerotherapy seeks to close an affected vein, while vein stripping physically removes the vein. Veins blocked via sclerotherapy or removed via stripping have negligible adverse effect on blood flow through the body, as the legs provide many alternative paths for blood flow. Problems generally do not return to treated veins, but new varicose veins may develop at other locations. Less commonly, laser or electro-cautery treatments may be used; such treatments may lead to scarring or changes in skin color. Regardless of which treatment option is chosen, the goal is to eliminate xe2x80x9cbadxe2x80x9d veins and force blood to flow through alternative healthy veins.
Vein stripping is commonly performed under local or partial anaesthesia. A medical practitioner ties off a patient""s affected vein above a varicose section. The practitioner then threads the distal end of a flexible device through the varicose section to a small incision near the patient""s groin or ankle. The proximal end of the device is attached to the varicose section. The practitioner then pulls the flexible device out of the patient through the incision, bringing with it, or xe2x80x9cstrippingxe2x80x9d, the varicose vein. Connecting veins that attach to deeper veins are tied off.
Vein stripping has been in clinical use since the 1950""s. Anaesthesia-related complications, including nausea and vomiting, may occur. Due to the invasiveness of the procedure, wound infection or scarring may be observed at the point of incision, and blood clots occasionally form.
Sclerotherapy involves insertion of a fine needle into a varicose vein. A therapeutic substance is injected through the needle directly into the vein. The sclerotherapeutic agent irritates an internal lining of the vein, causing inflammation, and, eventually, blood clotting and scarring that permanently blocks the vein. The body absorbs accumulated blood within the vein, and unsightly lumps flatten out over time. After injection, tissue surrounding the vein is wrapped in compression bandages for several days. Patients whose legs have been treated generally undertake a walking regimen to force blood to find alternative pathways, and to prevent blood clots distant from the point of treatment. Patients usually require multiple sclerotherapy treatment sessions.
Sclerotherapy and derivative methods have been in use since the 1920""s. Common sclerotherapeutic agents include hypertonic saline, sodium tetradecyl sulfate (xe2x80x9cSotradecolxe2x80x9d), and aethoxyskerol (xe2x80x9cPolidocanolxe2x80x9d). Complications may depend on the agent injected into the vein. Sotradecol triggers allergic reactions in some patients, occasionally severe. Hypertonic saline solution is less likely to cause allergic reactions, but either agent may burn the patient""s skin if the needle is not properly inserted, or may permanently mark or xe2x80x9cstainxe2x80x9d the skin.
A major drawback of current sclerotherapy techniques is that the injected agent is not localized at a treatment site, thereby reducing the efficacy of treatment and increasing systemic delivery of the agent. Occasionally, such systemic delivery leads to dangerous blood clot formation distant from the point of treatment.
In view of the drawbacks associated with previously known techniques for treating varicose veins, it would be desirable to provide apparatus and methods that overcome these drawbacks.
It would be desirable to provide methods and apparatus that reduce or eliminate blood clotting distant from a treatment site.
It also would be desirable to provide apparatus and methods for treating varicose veins that are localized and minimally invasive.
It would be desirable to provide apparatus and methods that reduce a quantity of foreign substances left in the body post-treatment.
In view of the foregoing, it is an object of the present invention to provide apparatus and methods for treating varicose veins that overcome the drawbacks of previously known techniques.
It is an object to reduce or eliminate blood clotting distant from a treatment site.
It is another object to provide apparatus and methods that are localized and minimally invasive.
It is yet another object of the present invention to reduce a quantity of foreign substances left in the body.
These and other objects are accomplished by providing apparatus comprising a catheter having an inflatable member for localized delivery of therapeutic agents. The catheter may be as described, for example, in U.S. Pat. No. 5,833,658 to Levy et al., or U.S. Pat. No. 5,611,775 to Machold et al. both of which are incorporated herein by reference.
In a preferred embodiment, the catheter has a guide wire lumen extending between its proximal and distal ends, and an inflation lumen extending between its proximal end and the inflatable member. The inflatable member comprises proximal and distal regions, and a central region disposed therebetween. The inflatable member is reversibly expandable from a collapsed delivery configuration to an expanded deployed configuration.
The central region of the inflatable member has a reduced cross-section in the deployed configuration, as compared to the proximal and distal regions. The central region further comprises one or more perforations extending through the inflatable member. When the inflatable member has been fully expanded to the deployed configuration via an inflation fluid delivered through the inflation lumen of the catheter, additional injection of a volume of the fluid causes a substantially equal volume of the fluid to exit through the one or more perforations.
When deployed in a blood vessel at a treatment site, the proximal and distal regions of the inflatable member sealingly engage an interior wall of the vessel, establishing an isolated vessel segment in the vicinity of the central region. Continued injection of the inflation fluid post-engagement of the vessel wall provides localized delivery of the inflation fluid to the isolated segment. Upon collapse of the inflatable member back to the delivery configuration by withdrawing the inflation fluid through the inflation lumen, a substantial portion, for example, a majority, of the inflation fluid delivered to the isolated segment is also withdrawn from the vessel through the perforations in the central region.
When the inflation fluid comprises a sclerotherapeutic agent, localized, minimally invasive sclerotherapy is achieved. The apparatus of the present invention may alternatively be used to locally deliver therapeutic agents to an isolated vessel segment in a variety of other intraluminal clinical applications, for example, to treat stenosis or restenosis.
Methods of using the apparatus of the present invention are also provided.